Ok, this will out me to a particular class of MNer, but:
A couple of years ago I went to a conference held in an American university. We were staying in the students' dorm rooms (and my god, they are puritanical! I was really sorry for those kids). Each room was connected to the next one by a shared bathroom. Sounds fine, right?
Only, the loo had no door at all, and while you could lock the door into your own room, you could not lock the door into the next room, so your neighbour had absolutely no way of knowing not to walk in on you, in full view, on the loo.
I am not especially prudish but it made me cringe. Imagine being 18 and paired up with someone you'd never met in your life, and coping with that?!
No door to the shower, either, so plenty of accidental nudity possibilities.
I do think parts of the US are quite prudish. All that no sex before marriage, silver ring kind of culture is. But it's such a huge country, I guess there's as much difference between different parts as there is between the US and the UK as countries.